Re: LN3 project possibility
The normal tricks applied to other engines apply just as well to the LN3. It'* a motor. Smoothing out the airflow into and out of the stock parts will work. Depending on the current condition, a basic overhaul, with matching of gasket flanges and clean injectors will make it better than original.
As mods: Do the 180 T-stat, a CAI with a good filter, get a scan tool, and check out how well it runs on the factory calibration. Get the scan tool first and use it on the car to see what it'* doing now...that will go a long way towards figuring out which systems are screwed up now and give you a baseline to compare back to.